The following article from Scientific American
is based on Edison's demonstration of his new invention at their office
on December 7, 1877. Phonozoic.net, dedicated to the history of the
phonograph and related media, transcribed this article for its web
site. This transcription is copied here, courtesy of Phonozoic.net,
followed by portions of the original newspaper article (Scientific
American, December 22, 1877, 384-5.)

THE TALKING PHONOGRAPH

Mr. Thomas A. Edison recently came into this
office, placed a little machine on our desk, turned a crank, and the
machine inquired as to our health, asked how we liked the phonograph,
informed us that it was very well, and bid us a cordial good night.
These remarks were not only perfectly audible to ourselves, but to
a dozen or more persons gathered around, and they were produced by
the aid of no other mechanism than the simple little contrivance explained
and illustrated below.

The principle on which the machine operates
we recently explained quite fully in announcing the discovery. There
is, first, a mouth piece, A, Fig. 1, across the inner orifice of which
is a metal diaphragm, and to the center of this diaphragm is attached
a point, also of metal. B is a brass cylinder supported on a shaft
which is screw-threaded and turns in a nut for a bearing, so that
when the cylinder is caused to revolve by the crank, C, it also has
a horizontal travel in front of the mouthpiece, A. It will be clear
that the point on the metal diaphragm must, therefore, describe a
spiral trace over the surface of the cylinder. On the latter is cut
a spiral groove of like pitch to that on the shaft, and around the
cylinder is attached a strip of tinfoil. When sounds are uttered in
the mouthpiece, A, the diaphragm is caused to vibrate and the point
thereon is caused to make contacts with the tinfoil at the portion
where the latter crosses the spiral groove. Hence, the foil, not being
there backed by the solid metal of the cylinder, becomes indented,
and these indentations are necessarily an exact record of the sounds
which produced them.

It might be said that at this point the machine
has already become a complete phonograph or sound writer, but it yet
remains to translate the remarks made. It should be remembered that
the Marey and Rosapelly, the Scott, or the Barlow apparatus, which
we recently described, proceed no further than this. Each has its
own system of caligraphy [sic], and after it has inscribed its peculiar
sinuous lines it is still necessary to decipher them. Perhaps the
best device of this kind ever contrived was the preparation of the
human ear made by Dr. Clarence J. Blake, of Boston, for Professor
Bell, the inventor of the telephone. This was simply the ear from
an actual subject, suitably mounted and having attached to its drum
a straw, which made traces on a blackened rotating cylinder. The difference
in the traces of the sounds uttered in the ear was very clearly shown.
Now there is no doubt that by practice, and the aid of a magnifier,
it would be possible to read phonetically Mr. Edison's record of dots
and dashes, but he saves us that trouble by literally making it read
itself. The distinction is the same as if, instead of perusing a book
ourselves, we drop it into a machine, set the latter in motion, and
behold! the voice of the author is heard repeating his own composition.

The reading mechanism is nothing but another
diaphragm held in the tube, D, on the opposite side of the machine,
and a point of metal which is held against the tinfoil on the cylinder
by a delicate spring. It makes no difference as to the vibrations
produced, whether a nail moves over a file or a file moves over a
nail, and in the present instance it is the file or indented foil
strip which moves, and the metal point is caused to vibrate as it
is affected by the passage of the indentations. The vibrations, however,
of this point must be precisely the same as those of the other point
which made the indentations, and these vibrations, transmitted to
a second membrane, must cause the latter to vibrate similar to the
first membrane, and the result is a synthesis of the sounds which,
in the beginning, we saw, as it were, analyzed.

In order to exhibit to the reader the writing
of the machine which is thus automatically read, we have had a cast
of a portion of the indented foil made, and from this the dots and
lines in Fig. 2 are printed in of course absolute facsimile, excepting
that they are level instead of being raised above or sunk below the
surface. This is a part of the sentences, "How do you do?" and "How
do you like the phonograph?" It is a little curious that the machine
pronounces its own name with especial clearness. The crank handle
shown in our perspective illustration of the device does not rightly
belong to it, and was attached by Mr. Edison in order to facilitate
its exhibition to us.

In order that the machine may be able exactly
to reproduce given sounds, it is necessary, first, that these sounds
should be analyzed into vibrations, and these registered accurately
in the manner described; and second, that their reproduction should
be accomplished in the same period of time in which they were made,
for evidently this element of time is an important factor in the quality
and nature of the tones. A sound which is composed of a certain number
of vibrations per second is an octave above a sound which registers
only half that number of vibrations in the same period. Consequently
if the cylinder be rotated at a given speed while registering certain
tones, it is necessary that it should be turned at precisely that
same speed while reproducing them, else the tones will be expressed
in entirely different notes of the scale, higher or lower than the
normal note as the cylinder is turned faster or slower. To attain
this result there must be a way of driving the cylinder, while delivering
the sound or speaking, at exactly the same rate as it ran while the
sounds were being recorded, and this is perhaps best done by well
regulated clockwork. It should be understood that the machine illustrated
is but an experimental form, and combines in itself two separate devices--the
phonograph or recording apparatus, and the receiving or talking contrivance
which reads it. Thus in use the first machine would produce a slip,
and this would for example be sent by mail elsewhere, together in
all cases with information of the velocity of rotation of the cylinder.
The recipient would then set the cylinder of his reading apparatus
to rotate at precisely the same speed, and in this way he would hear
the tones as they were uttered. Differences in velocity of rotation
within moderate limits would by no means render the machine's talking
indistinguishable, but it would have the curious effect of possibly
converting the high voice of a child into the deep bass of a man,
or vice versa.

No matter how familiar a person may be with
modern machinery and its wonderful performances, or how clear in his
mind the principle underlying this strange device may be, it is impossible
to listen to the mechanical speech without his experiencing the idea
that his senses are deceiving him. We have heard other talking machines.
The Faber apparatus for example is a large affair as big as a parlor
organ. It has a key board, rubber larynx and lips, and an immense
amount of ingenious mechanism which combines to produce something
like articulation in a single monotonous organ note. But here is a
little affair of a few pieces of metal, set up roughly on an iron
stand about a foot square, that talks in such a way, that, even if
in its present imperfect form many words are not clearly distinguishable,
there can be no doubt but that the inflections are those of nothing
else than the human voice.

We have already pointed out the startling possibility
of the voices of the dead being reheard through this device, and there
is no doubt but that its capabilities are fully equal to other results
just as astonishing. When it becomes possible as it doubtless will,
to magnify the sound, the voices of such singers as Parepa and Titiens
will not die with them, but will remain as long as the metal in which
they may be embodied will last. The witness in court will find his
own testimony repeated by machine confronting him on cross-examination--the
testator will repeat his last will and testament into the machine
so that it will be reproduced in a way that will leave no question
as to his devising capacity or sanity. It is already possible by ingenious
optical contrivances to throw stereoscopic photographs of people on
screens in full view of an audience. Add the talking phonograph to
counterfeit their voices, and it would be difficult to carry the illusion
of real presence much further.